The present invention relates to apparatus for converting stacks of superimposed paper sheets or the like into exercise books, steno pads or analogous stationery products. More particularly, the invention relates to improvements in so-called back stripping apparatus wherein the sheets of stacks of paper sheets, cardboard sheets and/or like sheets are united by adhesive-coated back strips which normally consist of textile material.
It is already known to connect the sheets of a stack of paper sheets or the like by resorting to adhesive-coated back strips which are normally made of a textile material and are caused to overlie and to be bonded to one edge portion and to the adjacent portions of the major surfaces of a stack of paper sheets or the like. As a rule, the stacks are delivered to and advanced past and beyond the back stripping station by a transporting system which is operated intermittently by a suitable prime mover. Heretofore known back stripping apparatus employ a conveyance which is movable back and forth in and counter to the direction of transport of the stacks and is provided with a support for the back strip which is about to be adhesively secured to a selected edge face of a stack of paper sheets or the like and with means for biasing the back strip against the selected edge face of the stack at the back stripping station. The stack which is about to be back stripped is supported by a table plate which is tilted in order to move the stack thereon against the adhesive-coated surface of the back strip on the conveyance. The conveyance is thereupon moved rearwardly whereby the stack withdraws a desired length of back strip material from a supply of such strip and the separated back strip is pressed against the selected edge face of the foremost stack. The separated portion of the web of coherent back strips is separated by a knife and the separated back strip is thereupon caused to advance through a system of rollers in order to fold the projecting marginal portions of the back strip over the adjacent major surfaces of the respective stack. Reference may be had to German Offenlegungsschrift No. 27 08 066.
A drawback of the just described conventional back stripping apparatus is its cost and complexity. Thus, the apparatus must employ a conveyance which must be provided with drive means for moving it back and forth in and counter to the direction of transport of stacks past the back stripping station. The mass of the conveyance is rather pronounced so that it cannot be moved back and forth at a very high frequency. Moreover, the apparatus must be provided with a table plate which is designed to move up and down in order to be in a position to bias a freshly separated back strip against the selected edge face of the oncoming stack of paper sheets or the like. Still further, the foremost back strip is caused to contact and to adhere to the marginal portion at the underside of the respective stack which automatically entails the need for repeated folding of the back strip about the selected edge face of the corresponding stack. In addition, the folding means of such apparatus is rather complex, expensive and prone to malfunction because it must be designed to prevent the formation of pleats or other irregularities which could detract from the appearance and/or other characteristics of the final products.